1. Field of the Invention
This invention relate to wiping of an inkjet print head, and a method of transferring a wetting liquid (solvent) to a wiper blade used in the wiping.
2. Description of the Related Art
U.S. Pat. No. 5,905,514 discloses a technique to wipe an ejection opening face with a wiper to which a low-volatile solvent (wetting liquid) is transferred one time for uniformizing the moistened state of the ejection opening at each wiping. For example, glycerin, polyethylene glycol or the like is used for the wetting liquid, which can dissolve a build-up of thickened ink or a built-up film deposited on the nozzle face. The interposition of the wetting liquid between the wiper and the nozzle face allows the wetting liquid to function as a lubricant, thus facilitating removal of foreign substance by wiping and protecting the ejection opening face. Wiping in which a low-volatile wetting liquid is transferred to a wiper one time and the wiper is used to wipe an ejection opening face as disclosed in U.S. Pat. No. 5,905,514 is hereinafter referred to as “wet wiping”.
In the wet wiping, a wetting liquid retaining member for receiving a wetting liquid and a transfer portion for applying a coat of the received wetting liquid to the wiper are provided in the main body of the printing apparatus. Typically, a fibrous member is used as the transfer portion, which is impregnated with the wetting liquid in the wetting liquid retaining member and stands by in that state. Then, the wiper is moved to come into contact with the transfer portion, so that a predetermined amount of the wetting liquid is transferred to the wiper. By performing a wiping operation to an ejection opening face of a print head using the wiper to which a wetting liquid is transferred in such a process, a preferred amount of the wetting liquid is applied to the ejection opening face.
In such wet wiping, the stability of the amount of the wetting liquid transferred to the wiper is desired for the purpose of maintaining ejection stability of the print head. However, the amount of the wetting liquid stored in the wetting liquid retaining member is decreased as the number of wiping operations is increased, along with which the speed at which the transfer portion is impregnated with the wetting liquid in the wetting liquid retaining member is decreased. As a result, the amount of the wetting liquid transferred to the wiper is also gradually decreased.
U.S. Patent publication No. 2007/0279452 discloses a technique for changing the amount of contact between the transfer portion and the wiper according to the amount of the wetting liquid remaining in the wetting liquid retaining member for the purpose of preventing such a reduction of the amount of the wetting liquid transferred to the wiper. Specifically, when the amount of the wetting liquid remaining in the wetting liquid retaining member is reduced to be equal to or less than a predetermined amount, the wetting liquid retaining member and the transfer portion go into standby in a downward moved position. By doing so, the intrusion amount of the wiper moving to make contact with the transfer portion (the length of a portion actually making contact with the transfer portion) is greater than that before those are moved downward, resulting in an increase in the contact area to which the wetting liquid can be transferred. Thus, even when a remaining amount of the wetting liquid is reduced to be small in the wetting liquid retaining member, it is possible to maintain a stable amount of wetting liquid application without a reduction in the amount of the wetting liquid applied to the wiper irrespective of the frequency and the duration of use of the printing apparatus.
In the structure in the related art, however, since the wiper horizontally moved makes contact with the transfer portion on standby, the wiper is acted upon by drag not only in the direction in which the wiper makes contact with the transfer portion but also in the moving direction of the wiper. In particular, in the structure disclosed in U.S. Patent publication No. 2007/0279452, as the amount of the wetting liquid remaining becomes the lower, the more the transfer portion is moved downward, resulting in a large intrusion amount of the wiper and an increased load thereon. Such a load is applied every time the wiper is moved to or evacuated from the transfer portion, that is, in each wiping operation, which accelerates deterioration of the wiper to cause shorter life.